Fitting the Replacement Alternator

[Theo]

I have a very little alternator at the moment. It delivers about 40A. I have been givine another recently reconditioned one which is said to deliver much more 90A IIRC. Here they are

 

 

The one above is the one fitted but I fear that it's not easy to see the connections.

 

 

This is the new one.

 

I don't know which wires go where on the new one. Could someone help, please?

 

Nick

[Tony Brooks]

I have a very little alternator at the moment. It delivers about 40A. I have been givine another recently reconditioned one which is said to deliver much more 90A IIRC. Here they are

 

 

The one above is the one fitted but I fear that it's not easy to see the connections.

 

 

This is the new one.

 

I don't know which wires go where on the new one. Could someone help, please?

 

Nick

 

 

Without the thing in front of me to inspect,

 

Yellow wire needs replacing with something far larger if it really is 90 amps and goes to the big nut with the red below it.

 

Capacitor with orange wire - forget it, if it causes radio interference through a steel hull you have problems.

 

Green wire which I think is the warning lamp wire (Pull it off and turn the ignition on, if the warning lmap is now out it is the warning lamp wire). Probbaly to the small terminal with teh red disk, but I can not be sure. It may be the other small terminal as long as it is insulated from the case. Sniblle will probably tell us soon I hope.

 

The brown flylead stuck out of the case. If you have an advanced regulator then you need the new alternator's voltage regulator modified to provide this connection. If it feeds a revcounter you need a phase tap. That might be the "other" small terminal, but you might need one fitting.

 

Looking at the cables I think you would be wise to stay with an advanced regulator if you have one, however not fitting the flylead shoddily not stop the alternator working.

[chris w]

I would guess the brown (under the yellow) is the ignition lamp and the green is the tacho. Others as per Tony.

 

The current alternator does indeed appear to have a connection for an alternator controller as Tony pointed out. If (Nick) you are not au fait with alternator wiring, you will need assistance to fit the wire for an external alternator controller to the new(!) alternator. You need to remove its regulator in order to get access to the field connection. Don't do this unless you know what you are doing.

 

Chris

Edited November 17, 2007 by chris w

[Tony Brooks]

I would guess the brown (under the yellow) is the ignition lamp and the green is the tacho. Others as per Tony.

 

The current alternator does indeed appear to have a connection for an alternator controller as Tony pointed out. If (Nick) you are not au fait with alternator wiring, you will need assistance to fit the wire for an external alternator controller to the new(!) alternator. You need to remove its regulator in order to get access to the field connection. Don't do this unless you know what you are doing.

 

Chris

 

 

Coo you'v got good eyesight chris. I never saw the brown one.

[RobinJ]

Coo you'v got good eyesight chris. I never saw the brown one.

I agree with Tony on this, as it looks like a BMC 1.5 with an old A127?

The yellow is the B+, the brown underneath the warning light. Not sure what the green wire is but could be an earth lead? The brown through the casing will be the tacho.

Have a look on the other for some marking, there should at leat be a B+ terminal marked.

[Sir Nibble]

Well Tony seems to have got it right and given all the right advice. Looking at where it enters the unit the brown wire is almost certainly the tacho connection, which Tony correctly identified as the small stud with brown insulator on the new unit. If you should choose to fit an external reg this is probably the easiest unit to do it to.

looks like a BMC 1.5 with an old A127?

The old alternator is an A115, a very reliable unit but only 45A output.

[chris w]

Well Tony seems to have got it right and given all the right advice. Looking at where it enters the unit the brown wire is almost certainly the tacho connection, which Tony correctly identified as the small stud with brown insulator on the new unit. If you should choose to fit an external reg this is probably the easiest unit to do it to.

 

The old alternator is an A115, a very reliable unit but only 45A output.

 

The brown wire which enters the unit was reckoned by Tony and me to be the external alternator field wire conection. You think it may be the tacho. If so and the other brown wire (under the yellow wire) is the charge lamp (D+) what is the green wire?

 

That's why I believe that the green wire is the tacho, the brown wire under the yellow one is the D+ and the other brown wire that goes through into the unit is the field wire.

 

What do you think?

 

Chris

[RobinJ]

The brown wire which enters the unit was reckoned by Tony and me to be the external alternator field wire conection. You think it may be the tacho. If so and the other brown wire (under the yellow wire) is the charge lamp (D+) what is the green wire?

 

That's why I believe that the green wire is the tacho, the brown wire under the yellow one is the D+ and the other brown wire that goes through into the unit is the field wire.

 

What do you think?

I bow to Snibble's judgement on the fact its an A115, but I thought that these alternators (at least older ones) didn't have a tacho connection and I knew the BMC 1.5 was normally fitted with an alternator tap!

As we have presumably identified the B+, warning light and tacho connection, that doesn't leave much left for the green wire?

If Theo has some sort of external regulator and this alternator has a tacho connection, then obviously we will need to re-assess!

I don't recognise the other unit, but it may well have a tacho connection. I would guess that the B+ has the big nut on, but of course thats not guaranteed!

[Sir Nibble]

From outside, we cannot be sure of the brown and green wires, one is going to be phase tap for the tacho, (as Robin says, these units did not often have a phase terminal) and the other is most likely an external reg. On a second look and knowing what is under that cover, I would suggest that the green is tacho, and the brown F-. Start the motor and see which of them kills the tacho when disconnected.

To wire the new unit for external reg, undo the 2 screws and remove the regulator/brushbox assembly, solder your field wire to the brush nearest the regulator body.

Terminals on the new alternator are: big stud, B+, smaller stud above with red insulator D+/61/wl, small stud with brown insulator W/ tacho. That much at least I can be sure of.

 

Edited to add:- Hang on, that wire I keep calling brown, is that orange? (not the one on the capacitor, the other one).

Edited November 19, 2007 by snibble

[Theo]

I would guess the brown (under the yellow) is the ignition lamp and the green is the tacho. Others as per Tony.The current alternator does indeed appear to have a connection for an alternator controller as Tony pointed out. If (Nick) you are not au fait with alternator wiring, you will need assistance to fit the wire for an external alternator controller to the new(!) alternator. You need to remove its regulator in order to get access to the field connection. Don't do this unless you know what you are doing.Chris

 

Just back from a few days working on the non electrical Theodora type things. Thanks for the timely warning, Chris.

 

There is a Kestrel controller present on the present setup. I believe that it might well be the Kestrel that is causing sufficient over voltage on a long run to cause my Sterling 1800W MSW inverter to trip out.

 

N

 

I agree with Tony on this, as it looks like a BMC 1.5 with an old A127?

 

The engine is certainly a BMC 1.5

 

N

 

Well Tony seems to have got it right and given all the right advice. Looking at where it enters the unit the brown wire is almost certainly the tacho connection, which Tony correctly identified as the small stud with brown insulator on the new unit. If you should choose to fit an external reg this is probably the easiest unit to do it to. The old alternator is an A115, a very reliable unit but only 45A output.

 

I am quite sorry that I have to change it, but 45A is not sufficient for my needs.

 

I have yet to decide if I am going to carry on with the Kestrel. I have heard very rude things said about it and understand why people don't like it. I was thinking that I might fit the "new" alternator without any sort of external reg and see how it performs

 

N

Edited November 21, 2007 by Theo
To add a bit

[RobinJ]

I have yet to decide if I am going to carry on with the Kestrel. I have heard very rude things said about it and understand why people don't like it. I was thinking that I might fit the "new" alternator without any sort of external reg and see how it performs

The Kestrel's serve a purpose, especially on old type aternators, if you have a newer alternator that has a multi stage controller, or a flashy all signing all dancing charge control regulator thingy, theres little point in having it fitted.

Mine has served me well and I've never had a problem with it (the last time the alternator regulator failed it actually got me home), but it does have the modification of the switch rather than the push button, so you can turn it off!

[Theo]

The Kestrel's serve a purpose, especially on old type aternators, if you have a newer alternator that has a multi stage controller, or a flashy all signing all dancing charge control regulator thingy, theres little point in having it fitted.

Mine has served me well and I've never had a problem with it (the last time the alternator regulator failed it actually got me home), but it does have the modification of the switch rather than the push button, so you can turn it off!

 

 

Mine has got the button.

 

It has occurred to me on reading another thread that the 40A that I can get from the present alternator might not be improved by fitting the new 70A jobbie and that I might be better advised to leave well alone.

 

What do you think?

 

One thing is certain. I am going to need to do some serious cable tracking and labelling on this boat before I touch anything. Although it is the only boat that I have ever worked on it seems to me that it is oddly wired up. Frinstance:

 

1. There is no way of knowing which battery you are drawing domestic "power" from unless you operate the battery isolators in the correct way. What a pain.

2. It has one of those big round 1, 2, both switches but that only seems to select which battery/ies are being charged not used.

 

I think that I need a day alone on the boat with a pencil, paper, a set of cable labels and a test meter.

 

I do like problem solving.

 

Nick

 

Nick

Edited November 22, 2007 by Theo
Add a bit

[RobinJ]

Mine has got the button.

I would advise you to have it modified so it can be turned off, its a safety feature just in case anything does go wrong.

1. There is no way of knowing which battery you are drawing domestic "power" from unless you operate the battery isolators in the correct way. What a pain.

2. It has one of those big round 1, 2, both switches but that only seems to select which battery/ies are being charged not used.

Irrespective of how the charge reaches each battery and whether you prefer to have a switch or a relay, the domestic should be wired to one battery and the engine stuff to the other, the only time thay will be physically connected is when the selector switch is on BOTH. I take it there are separate battery isolators on the delivery side to conforn with the BSS also.

[Theo]

I would advise you to have it modified so it can be turned off, its a safety feature just in case anything does go wrong.

 

Irrespective of how the charge reaches each battery and whether you prefer to have a switch or a relay, the domestic should be wired to one battery and the engine stuff to the other, the only time thay will be physically connected is when the selector switch is on BOTH. I take it there are separate battery isolators on the delivery side to conforn with the BSS also.

 

 

I see your point, Robin. The isolators are OK. As I said, having made good progress with the restoration, the time has come for a thorough investigation.

 

Nick

[Theo]

since ther was some discussion about the connection to the old alternator I thought that the best thing would be ito investigate to what each wire is connected before I do anything. I think that this might be useful to wnyone else with a similar alternator

 

This is what I discovered:

 

Thick yellow wire is poorly connected and needs urgent attention even if I decide to keep this alternator. It goas to the common or the 1, 2, both switch. What a relief!

 

The brown wire coming from the vent in the plastic case (top right) connects to the Kestrel

 

The green wire goes to the tacho.

 

The brown with just below the yellow B+ is, in fact brown with a while stripe and goes to the warning lamp.

 

Thanks all for your input. Teh job of tracing the wires was not made easier by the fact that some of the wires have several rusty terminal blocks in them and randomly change colour! Something to correct very soon!

 

Nick

[alan_fincher]

I'm reopening an old thread, because it has a lot of parallels to my situation.

 

The engine is a BMC 1800.

 

The alternator has previously identified by Snibble as an A115.

 

 

 

Some sources quote this as 45A max output, others lower than that.

 

What are my options for a straight swap to something with a higher output, please ?

 

At what kind of RPM would the higher output become significant - I seem to be reading the engine might need to be running harder to get the bigger outputs, or do I have that wrong ?

 

I don't mind changing terminations, but would like it to go on the same mounts, and use the same fan-belts, (there is no space to add extra pulleys, for example).

 

The existing alternator doesn't have an isolated negative, so it's replacement doesn't need to.

 

Is there any effective difference between the "marine" versions of reconditioned alternators being sold, and their automotive equivalents. There often seems to be a considerable premium for "marine".

Edited May 14, 2008 by alan_fincher

[RobinJ]

I'm reopening an old thread, because it has a lot of parallels to my situation.

The engine is a BMC 1800.

The alternator has previously identified by Snibble as an A115.

 

Some sources quote this as 45A max output, others lower than that.

What are my options for a straight swap to something with a higher output, please ?

There seems to be plenty of room and the 1800 will take almost any standard alternator (certainly up to 90A).

At what kind of RPM would the higher output become significant - I seem to be reading the engine might need to be running harder to get the bigger outputs, or do I have that wrong ?

The 1800 should have a larger pulley than the 1500 so the alternator normally works well from about 1500 rpm upwards (the normal minimum torque range).

I don't mind changing terminations, but would like it to go on the same mounts, and use the same fan-belts, (there is no space to add extra pulleys, for example).

It would appear that you only have B+ and W (or I) connection, so apart from swapping from lucar to eyelet and possibly increasing the capacity of the B+ wire you should find you have to do very little (you might have to adjust the spacers on the mounting).

Is there any effective difference between the "marine" versions of reconditioned alternators being sold, and their automotive equivalents. There often seems to be a considerable premium for "marine".

Those altenators truely designed for marine use, often have bigger fans and better heat dissipation to improve performance at high delivery for longer periods. Unless you are a heavy consumer with a large battery bank doing very little cruising its probably nothing to worry about.

[Sir Nibble]

I'm reopening an old thread, because it has a lot of parallels to my situation.

 

The engine is a BMC 1800.

 

 

What are my options for a straight swap to something with a higher output, please ?

 

At what kind of RPM would the higher output become significant - I seem to be reading the engine might need to be running harder to get the bigger outputs, or do I have that wrong ?

Sling an A127 on it. Lucas exchange LRA 461 should fit straight on with no mucking about at all. I disagree with Robin insofar as I cannot see any W terminal on your unit, just B+ and D+ so the terminal swap he mentioned isn't even required. I have a LRA461 on mt BMC 1800 and it seems fine at 1000 rpm cruise.

[alan_fincher]

Sling an A127 on it. Lucas exchange LRA 461 should fit straight on with no mucking about at all. I disagree with Robin insofar as I cannot see any W terminal on your unit, just B+ and D+ so the terminal swap he mentioned isn't even required. I have a LRA461 on mt BMC 1800 and it seems fine at 1000 rpm cruise.

 

Thank's both.

 

None of the terminals are marked in any way, nor is there any identification, stamped or printed on the alternator. Calcutt have done a sufficiently good job with their green paint that nothing has survived.

 

Id the "W" terminal the one that would drive a rev counter, please ? If so, my A115 doesn't have one. It would be good to have one on a replacement, as I wouldn't mind fitting a tacho at some stage.

 

Will this do it - it looks refreshingly cheap, and is "new" rather than "refurb" ?

 

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?Vie...e=WDVW&rd=1

 

Presumably I need some kind of puller to transfer the pulley and fan between the old and new ?

 

Many thanks,

 

Alan

[Sir Nibble]

Thank's both.

 

None of the terminals are marked in any way, nor is there any identification, stamped or printed on the alternator. Calcutt have done a sufficiently good job with their green paint that nothing has survived.

 

Id the "W" terminal the one that would drive a rev counter, please ? If so, my A115 doesn't have one. It would be good to have one on a replacement, as I wouldn't mind fitting a tacho at some stage.

 

Will this do it - it looks refreshingly cheap, and is "new" rather than "refurb" ?

 

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?Vie...e=WDVW&rd=1

 

Presumably I need some kind of puller to transfer the pulley and fan between the old and new ?

 

Many thanks,

 

Alan

That will do it, and has a W terminal clearly marked as standard. You cannot swap the pulley as the 115 has a 15mm shaft and the 127 17mm. Pulley should be available from any auto electrical specialist. Don't try and use the 8mm hex in the end of the rotor shaft to hold the thing whilst spannering the pulley nut, an air impact "buzz gun" is the best option.

Edited to add: yes, sorry, W is the rev counter terminal.

Edited May 15, 2008 by snibble

[RobinJ]

I disagree with Robin insofar as I cannot see any W terminal on your unit, just B+ and D+ so the terminal swap he mentioned isn't even required.

Sorry if I confised everybody!

Brown wire to the B+

Yellow wire to the warning light!

[Keeping Up]

As I posted on another thread - B for Battery, D for Dashboard, W for Whizzing-round-meter

 

(Doesn't help if you can't read the labels, of course)

[Sir Nibble]

As I posted on another thread - B for Battery, D for Dashboard, W for Whizzing-round-meter

 

(Doesn't help if you can't read the labels, of course)

True, but it does give a fascinating insight into your psychology.

[alan_fincher]

That will do it, and has a W terminal clearly marked as standard. You cannot swap the pulley as the 115 has a 15mm shaft and the 127 17mm. Pulley should be available from any auto electrical specialist. Don't try and use the 8mm hex in the end of the rotor shaft to hold the thing whilst spannering the pulley nut, an air impact "buzz gun" is the best option.

Edited to add: yes, sorry, W is the rev counter terminal.

Snibble,

 

Many thanks for your advice.

 

I ordered up a basic A127 alternator from e-Bay, sticking with a vehicle type rather than those badged "marine" which were a lot more.

 

I thought I had negotiated to get it supplied with fan and pulley pre-fitted, but that bit didn't work for some reason.

 

Fortunately I managed to get them added by a local vehicle electrics place for a fiver.

 

As you say, it went straight on to existing mounts, and even used same spade connector configuration.

 

It's about a centimetere "fatter" than the old A115, but just clears the panelling that boards off the side of the engine.

 

Will have to see how it performs in practice, but next replacement should probably be the old fashioned 30A-0-30A centre zero ammeter. Apart from dropping the voltage available for charging very marginally, it isn't goiung to tell me much if the alternator deliveres anything close to it's quoted 70 amps maximum.

 

The good news is I still have the old A115 as a spare.

 

Regards,

 

Alan

[Sir Nibble]

Snibble,

 

Many thanks for your advice.

 

I ordered up a basic A127 alternator from e-Bay, sticking with a vehicle type rather than those badged "marine" which were a lot more.

 

I thought I had negotiated to get it supplied with fan and pulley pre-fitted, but that bit didn't work for some reason.

 

Fortunately I managed to get them added by a local vehicle electrics place for a fiver.

 

As you say, it went straight on to existing mounts, and even used same spade connector configuration.

 

It's about a centimetere "fatter" than the old A115, but just clears the panelling that boards off the side of the engine.

 

Will have to see how it performs in practice, but next replacement should probably be the old fashioned 30A-0-30A centre zero ammeter. Apart from dropping the voltage available for charging very marginally, it isn't goiung to tell me much if the alternator deliveres anything close to it's quoted 70 amps maximum.

The good news is I still have the old A115 as a spare.

 

Regards,

 

Alan

 

and even used same spade connector configuration.

I would recommend that you remove the two B+ blade terminals and connect instead to the 6mm stud B+ terminal instead. Those "blade" (lucar) terminals are prone to cooking on higher output units.